Construction Of Iron Molybdate-based Z-scheme Heterojunctions And Their Applications In Pollutant Degradation

Water pollution caused by persistent organics has attracted worldwide attention.Both Fenton reaction and photocatalysis are belonged to the advanced oxidation technology,and have been considered as sustainable techniques for wastewater disposal,in which organics are degraded to small molecules such as H2 O and CO2 by various radicals.In recent two decades,although rapid developments have been made,a common bottleneck still exists in these two processes: low reaction rate.To solve this problem,heterogeneous Fenton reaction is coupled with photocatalytic process to construct photo-Fenton system.This method not only solves the disadvantages of the two technologies themselves,but also develops a more efficient advanced oxidation technology for wastewater treatment.In this paper,a novel photocatalyst Fe₂?MoO₄?₃ was selected as a target,and the corresponding Z-scheme photocatalyst and photo-Fenton reaction catalyst were constructed.Rhodamine B?Rh B?degradation was used as a model reaction to evaluate the catalytic performance,and the underlying mechanisms of these two catalysts were investigated.The detailed research is as follows:?1?Fe₂?MoO₄?₃/Ag₃PO₄ heterojunction was prepared via a co-precipitation method.The heterojunction with 7.0 wt% of Fe₂?MoO₄?₃ presented the best photocatalytic performance,and Rh B degradation efficiency reached 96.0% in 5.0min.The photocatalytic pathway was identified to follow Z-scheme routine via radical trapping experiments and band structure analysis.Compared with pristine Ag₃PO₄,Fe₂?MoO₄?₃/Ag₃PO₄ heterojunction displayed better reusability,since91.2% of degradation efficiency was remained within 20 min even after the 5th cycle.?2?Fe₂?MoO₄?₃/MoO₃ Z-scheme heterojunction was prepared via grinding-calcination method.In photocatalytic process,they displayed unsatisfying activity.Noteworthily,after adding H2O2,the degradation rate in photo-Fenton reaction was 57 and 170 times higher than those in Fenton reaction and photocatalytic reaction.The mechanism of the significantly increased degradation rate was explored: H2O2 not only served as oxidant in Fenton reaction,but also acted as scavenger of e-in photocatalytic reaction.Therefore,synergistic effect was established between Fenton reaction and Z-scheme photocatalysis via H2O2 as a bridge,and 1140% extra degradation efficiency was yielded by coupling two reactions.Besides high activity,superior cyclic stability was also demonstrated:92.6% of degradation efficiency was remained after the 5th cycle.This paper provides new avenues for preparing Fe₂?MoO₄?₃-based heterojunctions with superior activity in both photocatalytic reaction and photo-Fenton reaction toward the organic pollutant degradation.